Physical Models › Denormalization

Denormalization

You can also denormalize the structure of the logical model, or allow data redundancy in a table to improve query performance so that you can build a related physical model that is designed effectively for the target RDBMS. Features supporting denormalization include:

• Logical only properties for entities, attributes, key groups, and domains. You can mark any item in the logical model logical only so that it appears in the logical model, but does not appear in the physical model. For example, you can use the logical only settings to denormalize subtype relationships or support partial key migration in the physical model.
• Physical only properties for tables, columns, indexes, and domains. You can mark any item in the physical model physical only so that it appears in the physical model only. This setting also supports denormalization of the physical model since it enables the modeler to include tables, columns, and indexes in the physical model that directly support physical implementation requirements.
• Resolution of many-to-many relationships in a physical model. Support for resolving many-to-many relationships is provided in both the logical and physical models. If you resolve the many-to-many relationship in the logical model, the associative entity is created and lets you add additional attributes. If you choose to keep the many-to-many relationship in the logical model, you can still resolve the relationship in the physical model. The link is maintained between the original logical design and the new physical design, so the origin of the associative table is documented in the model.